Thursday, July 10, 2014

Ranking World Cup Rating Systems

Before the World Cup began we looked at what some rating systems predicted from the group stage.  To recap, the four rating systems we looked at were:

Elo: Originally devised as a method to rank world chess players, it is one of the most robust international soccer rating systems.
SPI: Developed for ESPN by famed political prognosticator Nate Silver.  
Oddsportal: An aggregator of 10+ online betting house odds.  Reflects the opinion of the betting public.
EA Sports FIFA Video Game: Based on player and team ratings provided by the popular video game franchise.

When we ran each system's match-by-match projections, certain geographical biases became noticeable (see below).

To re-iterate, we only looked at group stage games, and projected results were not modified as games were played.  In essence, the projections represent a "freeze frame" from before the World Cup began. Many other people have been tracking the rating systems, perhaps most notably Seth Burns over at Stats Bomb, who has been making "bets" following Nate Silver's SPI model.


Granted, the differences between each rating system might seem small, but don't be fooled. Over the course of 48 games (still a small sample size) it is significant that both Elo and SPI clearly outperform Oddsportal.  If you clicked on the Seth Burns link  you would see that by betting with SPI during the group stage you would have ended up over 600%!

Breaking the results down by region confirms what everyone knew watching the group stages:  the Americas came to play, while Asian teams were largely disappointing.

No comments:

Post a Comment